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Progress Toward Poliomyelitis Eradication --- Egypt, 2001
The 1988 World Health Assembly resolved to eradicate poliomyelitis worldwide by 2000. Since then, the estimated number of polio cases has decreased by >99%. The Americas and the Western Pacific regions of the World Health Organization (WHO) have been certified polio-free (1,2), and it is expected that the European Region will be certified this year. Progress also has been made in the Eastern Mediterranean Region (EMR), where polio is endemic in five of 22 countries (Afghanistan, Egypt, Pakistan, Somalia, and Sudan) (3). This report summarizes progress toward polio eradication from 1997 through 2001 in Egypt, where several independent chains of wild poliovirus type 1 continue to circulate despite a long history of eradication efforts. The findings indicate the need to improve surveillance and vaccination activities.
Since 1968 in Egypt, routine vaccination coverage of infants with >3 doses of oral poliovirus vaccine (OPV) has increased steadily, and has been >90% since 1994. In 2001, the reported routine coverage was >95% nationwide with only five of 245 districts reporting levels <90%*.
Since 1976, Egypt has been conducting OPV supplementary vaccination activities and in 1989 began implementing annual National Immunization Days (NIDs). The campaigns have improved substantially since 2000, with house-to-house vaccine delivery extended to urban areas in Upper Egypt and to high-risk areas and slums in Lower Egypt. Microplanning at the local level was implemented during 2001. The Ministry of Health and Population (MOHP) intensified supervision in high-risk areas using monitors from outside MOHP. MOHP conducted extensive supplementary vaccination activities in Upper Egypt during 2001, with targeted campaigns in selected districts of seven governorates in July and August, three subnational rounds in all of Upper Egypt in March, April, and September, and three NID rounds in January, November, and December. Thus, high-risk areas in Upper Egypt were covered by eight rounds over a 12-month period in 2001.
Surveillance for acute flaccid paralysis (AFP) was initiated in Egypt in August 1990 (4). Surveillance performance has improved during the past 5 years (Table 1). The national target level of sensitivity (>1 nonpolio AFP case per 100,000 children aged <15 years) has been reached each year since 1998. The 252 AFP cases in 2001 were reported from 23 of the 27 governorates, representing approximately 98% of the population. Three of the four governorates that reported no AFP have small populations. Fifteen governorates achieved nonpolio AFP rates of >1.
All stool samples collected from AFP cases were tested at the national polio laboratory (Vacsera), which is accredited by WHO as a regional reference laboratory in the global poliovirus laboratory network. Since 1996, genetic sequence analyses have been performed routinely on all wild poliovirus isolates detected in Egypt. Results indicate that all are closely related to poliovirus lineages that have been indigenous to Egypt for >5 years. The genetic sequence data also highlight progress being made, with decreasing genetic diversity of polioviruses and fewer lineages surviving each successive low transmission season.
Even with improved case detection, the number of confirmed cases of polio has decreased from 100 in 1996 to five in 2001. Poliovirus type 2 was last detected in Egypt in 1994; types 1 and 3 were isolated in 2000 and only type 1 was isolated in 2001.
Since late 1999, wild poliovirus detection through AFP surveillance has been localized in a few districts of Upper Egypt. In 2000, four virologically confirmed polio cases were detected in three governorates: Asyut Governorate (one type 1 with January onset and one type 3 with February onset), Qena Governorate (one type 1 with May onset), and Fayoum Governorate (one type 3 with December onset). In 2001, five type 1 virologically confirmed polio cases were reported in Egypt: three from Minya Governorate (one January onset case from Malawi district, and two from Abu Qurqas district with onsets in January and February) and two from Qena Governorate (October and November onsets).
During 1999--2001, 18 patients with virologically confirmed cases were aged 7--19 months. Among 13 patients reported in 1999 and 2000, two had received <3 valid§ doses of OPV, while the other 10 patients received 4--7 valid doses through either routine or supplementary vaccination. All five patients reported in 2001 received >6 valid doses.
In July 2000, MOHP began to supplement AFP surveillance with environmental surveillance (i.e., collecting and testing wastewater samples) for the presence of wild polioviruses. Ten sampling sites were selected in seven governorates of Upper Egypt: Minya, Fayoum, Beni Suef, Asyut, Sohag, Aswan, and Qena. One site was selected from Gharbia Governorate in Lower Egypt.
During September 2000--December 2001, a total of 194 samples were tested; 64 (33%) yielded wild poliovirus type 1. Wild poliovirus was detected in every study governorate. All isolates were characterized further by partial genomic sequencing, which indicated that the viruses from wastewater samples were closely related to the type 1 polioviruses isolated from paralytic cases. The genetic data indicate that a single genotype of poliovirus type 1 virus with multiple lineages has persisted in Egypt >6 years.
Reported by: Regional Office for the Eastern Mediterranean Region, Cairo, Egypt. Dept of Vaccines and Biologicals, World Health Organization, Geneva, Switzerland. Div of Viral and Rickettsial Diseases, National Center for Infectious Diseases; Global Immunization Div, National Immunization Program, CDC.
Before the eradication initiative, Egypt was one of the most intensely polio-endemic countries in the world. The conditions that contributed to intense transmission, such as extremely high population density and poor sanitation, still exist and pose important challenges to disease eradication efforts. To interrupt transmission, it is essential to sustain high-quality surveillance and conduct well-organized vaccination activities.
Case investigations and reports from independent monitors in Upper Egypt have identified several barriers to polio eradication, including delayed or missed birth registrations, delayed routine vaccination doses, difficult-to-reach areas with poor access to health services, and irregular outreach activities. In past years, security concerns resulted in restricted access to some children. In some areas, cold chain problems have threatened the quality of the vaccine being administered. Other barriers identified were an insufficient number of field supervisors during vaccination campaigns and an insufficient number of vaccination teams to conduct a house-to-house vaccination strategy, especially in urban areas. Finally, some surveillance deficiencies were noted at the subnational level, with a lack of active surveillance in some areas.
To reduce these barriers, MOHP, with assistance from WHO, has assessed and rehabilitated the cold chain, introduced Vaccine Vial Monitors for OPV used in both campaigns and routine vaccination, and tested the quality of the OPV being used. MOHP has used community census data to prepare local registers of children for tracking routine vaccination and strengthened the system for tracing children with insufficient vaccination. To improve vaccination coverage, MOHP has included an optional birth dose of OPV for children born in Upper Egypt, implemented high-quality targeted campaigns in Upper Egypt and other high-risk areas, and raised the upper age limit of children targeted for supplemental activities from 4 to 5 years. Finally, MOHP has improved the AFP surveillance system by involving both private and university hospitals and clinics.
Conditions in Egypt are probably particularly favorable for intense poliovirus transmission. The continued transmission of wild poliovirus after many years of intense efforts reflects the need to implement fully in Egypt those strategies that have proved successful in other parts of the world, such as intensified searching for cases and high-quality house-to-house campaigns. The intensified eradication strategies require the full support of all of the agencies and organizations involved.
WHO continues to seek the opinions and support of international experts. Several consultations have been held in the past 3 years. A recently established Technical Advisory Group held its inaugural meeting and review in March 2002. If poliovirus transmission is to be interrupted in Egypt, the eradication effort will require sustained political support of the Egyptian government, high-quality program execution by MOHP, and technical support from WHO and others.
* Coverage calculated by using the number of OPV doses administered as the numerator and the number of registered infants as the denominator.
Mass campaigns over a short period (days) in which 2 doses of OPV are administered to all children in the target group (usually those aged <5 years) regardless of previous vaccination history.
§ Doses of OPV administered >4 weeks apart.
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